High Speed Downlink Packet Access (HSDPA) is a technology proposed by the 3rd Generation Partnership Project (3GPP) in Release-5, and is used for increasing a network data throughput in a downlink direction, namely, from a network side to a UE, wherein a downlink peak rate designed for the technology can reach 14.4 Mbps.
In a design of a physical layer, the HSDPA adopts a High Speed-Physical Downlink Shared Channel (HS-PDSCH) in a downlink direction to carry data of a High Speed-Downlink Shared Channel (HS-DSCH). Moreover, a High Speed-Shared Control Channel (HS-SCCH), which is transmitted before its corresponding HS-PDSCH, is used in the downlink direction for notifying UE of some necessary information about the HS-PDSCH transmitted after the HS-SCCH, such as a spreading code, a modulation method, the size of a transmission block, the process of a Hybrid Automatic Repeat Request (HARQ),a redundancy release, a new data indication, and a UE identifier which are used, so that the UE designated by the UE identifier can receive data transmitted by the HS-PDSCH correctly while other UE can not receive the data transmitted by the HS-PDSCH.
In an uplink direction, the HSDPA adopts a dedicated physical control channel for the HS-DSCH, namely a High Speed-Dedicated Physical Control Channel (HS-DPCCH). Through the HS-DPCCH, the UE feeds back to the network side that whether a transmission block in the HS-DSCH is received correctly or not, wherein ACK means correct reception, while NACK means incorrect reception, thus the corresponding data needs to be retransmitted, based on this the network side performs retransmission or transmits new data. Besides, the UE also feeds back a Channel Quality Indicator (CQI) table. The CQI table is predefined, and each CQI value corresponds to an HS-DSCH subframe in which the size of the transmission block, the quantity of HS-PDSCHs, and the modulation method are fixed. The UE should feed back a maximum CQI, which indicates that if the HS-DSCH subframe corresponding to the maximum CQI is received by the UE in one time slot prior to the moment when the HS-DPCCH subframe carrying the CQI starts transmitting, then error probability of the corresponding transmission block is not more than 10%, and this will be taken as a reference of radio channel quality of the UE.
In a design of an HS-DPCCH, HARQ-ACK information is carried by 10-bit data, and CQI information is carried by 20 bits. According to different capabilities, each UE belongs to a specific category (a UE category), the CQI table corresponding to the UE category contains 31 items which can be expressed by 5-bit data, and encoded into 20 bits and mapped in a CQI bit field of the HS-DPCCH. Two situations, i.e. ACK and NACK, may exist in an HARQ, which respectively indicate that a data block is received correctly and there is an error in the received data block. ACK or NACK is encoded into 10 bits through a specific code book, and then is mapped in an HARQ-ACK bit field of the HS-DPCCH.
Later, the 3GPP makes enhancement in several aspects based on the HSDPA. A Multiple-Input Multiple-Output (MIMO) antenna technology is one of the methods for improving the transmission bandwidth of a radio channel. The 3GPP adopts the MIMO technology in Rel-7 to ensure that at most two transmission blocks (a main transmission block and an auxiliary transmission block) are transmitted to one UE in a Transmission Time Interval (TTI) of 2 ms simultaneously. In order to support the MIMO technology, a sender needs to modulate data onto two incoherent antennae and transmit the data simultaneously, and a receiver also needs to receive the data from the two incoherent antennae simultaneously and demodulate the data. Similar to the HSDPA, the UE also needs to feed back HARQ-ACK and CQI after receiving HS-DSCH data. While different to the HSDPA, the UE needs to feed back HARQ-ACK for the two HS-DSCH transmission blocks respectively which are received simultaneously, and the CQI also aims at two spatial channels, and is marked as CQI1 and CQI2. Furthermore, UE also needs to feed back an antenna array weight, namely a precoding weight, required by a closed loop MIMO, so as to maximize the size of a transmission block. There are four precoding weights, namely w1, w2, w3 and w4; wherein (w1, w2) constitute a main precoding vector for weighting data of a main transmission block, and (w3, w4) constitute an auxiliary precoding vector for weighting data of an auxiliary transmission block. The main precoding vector is used for transmitting the main transmission block, and the auxiliary precoding vector is used for transmitting the auxiliary transmission block. In the four precoding weights, w1 and w3 are fixed values, and w2 and w4 have fixed symbol relation, therefore UE only needs to feed back the precoding weight w2, which is realized through a Precoding Control Indicator (PCI). w2 may be one of four values, so the PCI is 2-bit data. In case of MIMO, a new CQI table is used, and a CQI table corresponding to each specific UE category contains 15 items which are expressed by 4-bit data, so CQI1 and CQI2 need 8 bits in total. Therefore, the PCI and the CQI are 10-bit data after being combined together and are encoded into 20 bits to be mapped in a CQI/PCI bit field (namely the original CQI bit field) of the HS-DPCCH. An HARQ needs to consider the combination of six situations of ACK/NACK under conditions of single current and double current, and ACK/NACK is encoded into 10 bits through a specific code book to be mapped in an HARQ-ACK bit field of an HS-DPCCH.
The MIMO technology improves bandwidth by increasing the number of antennae at both the sender and the receiver. If the MIMO technology is not adopted, bandwidth can also be improved by a method of increasing carriers. In order to further improve the downlink bandwidth, the 3GPP introduces a Double Carrier HSDPA (DC-HSDPA) technology in Rel-8, and the downlink bandwidth is improved through two adjacent carriers (a main carrier and an auxiliary carrier). An HS-PDSCH and an HS-SCCH are both set for the main carrier and the auxiliary carrier, and the main carrier and the auxiliary carrier are scheduled independently. For a UE with the capability of receiving DC-HSDPA, HSDPA data can be received at both the main carrier and the auxiliary carrier. Similar to a single carrier HSDPA, the UE needs to feed back HARQ-ACK and CQI after receiving HS-DSCH data; while different to the single carrier HSDPA, the UE needs to feed back HARQ-ACK for the two HS-DSCH transmission blocks respectively which are received on two carriers simultaneously, and the CQI also aims at the two carriers, and is marked as CQI1 and CQI2. A CQI table corresponding to each CQI contains 31 items which can be expressed by 5-bit data, CQI1 and CQI2 are 10-bit data in total and are encoded into 20-bit data to be mapped in a CQI bit field of an HS-DPCCH. An HARQ needs to consider the combination of eight situations of ACK/NACK under the conditions of single carrier and multicarrier, and ACK/NACK is encoded into 10 bits through a specific code book to be mapped in an HARQ-ACK bit field of an HS-DPCCH.
In order to further improve the downlink bandwidth, the 3GPP combines the DC-HSDPA with the MIMO in Rel-9. In a design of an HS-DPCCH, based on an overall consideration of performance and power consumption, one HS-DPCCH is still adopted for information feedback. HARQ needs to consider the combination of forty-eight situations of ACK/NACK under the conditions of main carrier, auxiliary carrier, single current and multi-current, and ACK/NACK is encoded into 10 bits through a specific code book to be mapped in an HARQ-ACK bit field of the HS-DPCCH. A PCI needs to provide feedback with respect to the main carrier and the auxiliary carrier respectively, and is marked as PCI1 and PCI2 which are 4-bit data in total. A CQI is defined by using a MIMO CQI table of Rel-7; both CQI1 and CQI2 exist on each carrier and are 8-bit data; so the CQI1 and CQI2 existing on the main carrier and the auxiliary carrier are 16-bit data in total. Or, the CQI/PCI of the main carrier is 10-bit data, and the CQI/PCI of the auxiliary carrier is also 10-bit data. In HS-DPCCH transmission, the CQI/PCI of the main carrier is 10-bit data in total and is encoded into 20 bits to be mapped in a CQI/PCI bit field of a subframe in two continuous subframes of the HS-DPCCH; and the CQI/PCI of the auxiliary carrier is 10-bit data in total and is encoded into 20 bits to be mapped in a CQI/PCI bit field of another subframe in the two continuous subframes of the HS-DPCCH. That is to say, the CQI/PCI data of the main and the auxiliary carriers is transmitted on the HS-DPCCH in a time division multiplex manner.
In order to further improve the user peak rate, more carriers need to be combined together to be transmitted, for example, no less than four carriers (4C for short below) need to be combined together when MIMO data is transmitted at the bandwidth of 20 MHz, wherein each carrier can support HSDPA and MIMO. HARQ information that each carrier needs to feed back is one of the seven situations as follows: A, N, D, AA, AN, NA and NN. According to the existing transmission method of HARQ feedback information, the number of combination needing to be considered under the condition of four carriers is as follows: 7×7×7×7−1=2400, while a data field that carries the HARQ feedback information is 10 bits, which can feed back 1024 situations at most, therefore the feedback requirement of the HARQ information goes far beyond the carrying capacity of a 10-bit data field. Accordingly, a new HARQ transmission method is required to meet the transmission requirement of the HARQ information under the condition of four carriers where HSDPA is combined with MIMO, and the capability of UE also needs to be improved. Although a capability that UE supports double-carrier is introduced when double carriers are introduced into R8 protocol, for the condition of supporting four carriers, the capability that UE supports double-carrier can not express a capability that UE supports multicarrier; and the network side can not accurately learn that the UE can support multicarrier, so as not to allocate resources reasonably.